00008583722012-08-022013-08-010000858372cat:S000006301Membercat:CapitalAssetsFundsSharesMembercat:C000017335Member2012-08-022013-08-010000858372cat:S000006301Membercat:CapitalAssetsFundsSharesMember2012-08-022013-08-010000858372cat:S000006303Membercat:CapitalAssetsFundsSharesMembercat:C000017345Member2012-08-022013-08-010000858372cat:S000006303Membercat:CapitalAssetsFundsSharesMember2012-08-022013-08-01pureiso4217:USDOther2013-09-25CASH ACCOUNT TRUST0000858372false2013-09-252013-09-252013-08-0100.00050.00330.00640.010210432556312480.0410.0430.01580.00020.00010.00010.00012005-05-130.00010.00320.0151Year-to-Date2013-06-300Best Quarter:2006-09-300.011Worst Quarter:2011-03-310<b>Government &amp; Agency Securities Portfolio</b><b>Investment Objective</b>The fund seeks to provide maximum current income consistent with stability of capital.<b>Fees and Expenses of the Fund</b>These are the fees and expenses you may pay when you buy and hold shares.<b>SHAREHOLDER FEES</b><br/><br/>(paid directly from your investment)<b>ANNUAL FUND OPERATING EXPENSES<br/>(expenses that you pay each year as a % of the value of your investment)</b><b>EXAMPLE</b>This Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:<b>Principal Investment Strategy</b>The fund is managed in accordance with Rule 2a-7 under the Investment Company Act of 1940, as amended, which governs the quality, maturity, diversity and liquidity of instruments in which a money market fund may invest.<br/><br/>The fund pursues its objective by investing exclusively in the following types of investments:<ul type="square"><li style="margin-left:20px">US Treasury bills, notes, bonds and other obligations issued or guaranteed by the US government, its agencies or instrumentalities.</li><li style="margin-left:20px">Repurchase agreements backed by these securities. In a repurchase agreement, the fund buys securities at one price with a simultaneous agreement to sell back the securities at a future date at an agreed-upon price.</li></ul> The fund may invest in floating and variable rate instruments (obligations that do not bear interest at fixed rates).<br/><br/> Working in consultation with portfolio management, a credit team screens potential securities and develops a list of those that the fund may buy. Portfolio management, looking for attractive yield and weighing considerations such as credit quality, economic outlooks and possible interest rate movements, then decides which securities on this list to buy.<b>Main Risks</b>There are several risk factors that could reduce the yield you get from the fund, cause the fund's performance to trail that of other investments, or cause you to lose money.<br/><br/><b>Money market fund risk.</b> An investment in the fund is not insured or guaranteed by the FDIC or any other government agency. Although the fund seeks to preserve the value of your investment at $1.00 per share, this share price isn't guaranteed, and if it falls below $1.00 you would lose money. The Advisor is not obligated to take any action to maintain the $1.00 share price. The share price could fall below $1.00 as a result of the actions of one or more large investors in the fund. The credit quality of the fund's holdings can change rapidly in certain markets, and the default of a single holding could cause the fund's share price to fall below $1.00, as could periods of high redemption pressures and/or illiquid markets.<br/><br/><b>Interest rate risk.</b> Rising interest rates could cause the value of the fund's investments &#151; and therefore its share price as well &#151; to decline. Conversely, any decline in interest rates is likely to cause the fund's yield to decline, and during periods of unusually low interest rates, the fund's yield may approach zero. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of current income and, at times, could impair the fund's ability to maintain a stable $1.00 share price. Over time, the total return of a money market fund may not keep pace with inflation, which could result in a net loss of purchasing power for long-term investors.<br/><br/><b>Security selection risk.</b> Although short-term securities are relatively stable investments, it is possible that the securities in which the fund invests will not perform as expected. This could cause the fund's returns to lag behind those of similar money market funds and could result in a decline in share price.<br/><br/><b>Repurchase agreement risk.</b> If the party that sells the securities to the fund defaults on its obligation to repurchase them at the agreed-upon time and price, the fund could lose money.<br/><br/><b>Counterparty risk.</b> A financial institution or other counterparty with whom the fund does business, or that underwrites, distributes or guarantees any investments or contracts that the fund owns or is otherwise exposed to, may decline in financial health and become unable to honor its commitments. This could cause losses for the fund or could delay the return or delivery of collateral or other assets to the fund.<br/><br/><b>Credit risk.</b> The fund's performance could be hurt and the fund's share price could fall below $1.00 if an issuer of a money market instrument suffers an adverse change in financial condition that results in a payment default, security downgrade or inability to meet a financial obligation.<br/><br/>Some securities issued by US government agencies or instrumentalities are backed by the full faith and credit of the US government. Other securities that are supported only by the credit of the issuing agency or instrumentality are subject to greater credit risk than securities backed by the full faith and credit of the US government. This is because the US government might provide financial support, but has no obligation to do so, if there is a potential or actual loss of principal or failure to make interest payments.<br/><br/>Because of the rising US government debt burden, it is possible that the US government may not be able to meet its financial obligations or that securities issued by the US government may experience credit downgrades. Such a credit event may also adversely impact the financial markets.<br/><br/><b>Liquidity risk.</b> The liquidity of portfolio securities can deteriorate rapidly due to credit events affecting issuers or guarantors or due to general market conditions and a lack of willing buyers. When there are no willing buyers and an instrument cannot be readily sold at a desired time or price, the fund may have to accept a lower price or may not be able to sell the instrument at all. An inability to sell one or more portfolio securities can adversely affect the fund's ability to maintain a $1.00 share price or prevent the fund from being able to take advantage of other investment opportunities.<br/><br/>Unusual market conditions, an unusually high volume of redemption requests or other similar conditions could cause the fund to be unable to pay redemption proceeds within a short period of time. If the fund is forced to sell securities at an unfavorable time and/or under unfavorable conditions, such sales may adversely affect the fund's ability to maintain a $1.00 share price.<br/><br/><b>Prepayment and extension risk.</b> When interest rates fall, issuers of high interest debt obligations may pay off the debts earlier than expected (prepayment risk), and the fund may have to reinvest the proceeds at lower yields. When interest rates rise, issuers of lower interest debt obligations may pay off the debts later than expected (extension risk), thus keeping the fund's assets tied up in lower interest debt obligations. Ultimately, any unexpected behavior in interest rates could increase the volatility of the fund's yield and could hurt fund performance. Prepayments could also create capital gains tax liability in some instances.<br/><br/><b>Regulatory risk.</b> In June 2013, the SEC proposed money market fund reform intended to address perceived systemic risks associated with money market funds and to improve transparency for money market fund investors. The Financial Stability Oversight Council (FSOC), a board of U.S. regulators established by the Dodd-Frank Act, had also previously proposed similar recommendations for money market fund reform. If one or more of the SEC or FSOC proposals for money market fund reform were to be adopted in the future, such regulatory action may affect the fund's operations and/or return potential.<b>Past Performance</b>How a fund's returns vary from year to year can give an idea of its risk. Past performance may not indicate future results. All performance figures below assume that dividends were reinvested. The <b>7-day yield,</b> which is often referred to as the "current yield," is the income generated by the fund over a seven-day period. This amount is then annualized, which means that we assume the fund generates the same income every week for a year. For more recent performance figures and the current yield, go to www.dws-investments.com (the Web site does not form a part of this prospectus) or call the phone number included in this prospectus.<b>CALENDAR YEAR TOTAL RETURNS (%) (Capital Assets Funds Shares)</b>Returns for other classes were different and are not shown here.Best Quarter: 1.10%, Q3 2006 Worst Quarter: 0.00%, Q1 2011<br/>Year-to-Date as of 6/30/13: 0.00%<b>Average Annual Total Returns<br/>(for periods ended 12/31/2012 expressed as a %)</b>Total returns would have been lower if operating expenses hadn't been reduced.<br/><br/>Apex Clearing Corporation, the sole sub-distributor of Capital Assets Funds Shares, may periodically waive fees in order to maintain minimum yield levels. These waivers may be changed or terminated at any time without notice. For more recent performance information, contact the financial services firm from which you obtained this prospectus.There are several risk factors that could reduce the yield you get from the fund, cause the fund's performance to trail that of other investments, or cause you to lose money.<b>Money market fund risk.</b> An investment in the fund is not insured or guaranteed by the FDIC or any other government agency. Although the fund seeks to preserve the value of your investment at $1.00 per share, this share price isn't guaranteed, and if it falls below $1.00 you would lose money. The Advisor is not obligated to take any action to maintain the $1.00 share price. The share price could fall below $1.00 as a result of the actions of one or more large investors in the fund. The credit quality of the fund's holdings can change rapidly in certain markets, and the default of a single holding could cause the fund's share price to fall below $1.00, as could periods of high redemption pressures and/or illiquid markets.An investment in the fund is not insured or guaranteed by the FDIC or any other government agency.How a fund's returns vary from year to year can give an idea of its risk.www.dws-investments.comPast performance may not indicate future results.00.00060.00330.00640.010310532856912590.0010.00260.01440.02470.0270.01380.00020.00010.00020.00022005-05-130.00020.00290.0084Year-to-Date2013-06-300.0002Best Quarter:2007-06-300.007Worst Quarter:2003-09-300<b>Tax-Exempt Portfolio</b><b>Investment Objective</b>The fund seeks to provide maximum current income that is exempt from federal income taxes to the extent consistent with stability of capital.<b>Fees and Expenses of the Fund</b>These are the fees and expenses you may pay when you buy and hold shares.<b>SHAREHOLDER FEES</b><br/><br/>(paid directly from your investment)<b>ANNUAL FUND OPERATING EXPENSES<br/>(expenses that you pay each year as a % of the value of your investment)</b><b>EXAMPLE</b>This Example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:<b>Principal Investment Strategy</b>The fund normally invests at least 80% of its net assets in municipal securities, the income from which is free from regular federal income tax and alternative minimum tax (AMT). This policy is fundamental and may not be changed without shareholder approval.<br/><br/>The fund is managed in accordance with Rule 2a-7 under the Investment Company Act of 1940, as amended, which governs the quality, maturity, diversity and liquidity of instruments in which a money market fund may invest.<br/><br/>The fund may invest in municipal trust securities (MTRs), general obligation and revenue notes and bonds, municipal obligations backed by third parties and other municipal instruments paying a fixed, variable or floating interest rate.<br/><br/>The fund is designed for investors in a moderate to high tax bracket who are interested in federal tax-free income along with the liquidity and stability that a money market fund is designed to offer.<br/><br/>Working in consultation with portfolio management, a credit team screens potential securities and develops a list of those that the fund may buy. Portfolio management, looking for attractive yield and weighing considerations such as credit quality, economic outlooks and possible interest rate movements, then decides which securities on this list to buy.<b>Main Risks</b>There are several risk factors that could reduce the yield you get from the fund, cause the fund's performance to trail that of other investments, or cause you to lose money.<br/><br/><b>Money market fund risk.</b> An investment in the fund is not insured or guaranteed by the FDIC or any other government agency. Although the fund seeks to preserve the value of your investment at $1.00 per share, this share price isn't guaranteed, and if it falls below $1.00 you would lose money. The Advisor is not obligated to take any action to maintain the $1.00 share price. The share price could fall below $1.00 as a result of the actions of one or more large investors in the fund. The credit quality of the fund's holdings can change rapidly in certain markets, and the default of a single holding could cause the fund's share price to fall below $1.00, as could periods of high redemption pressures and/or illiquid markets.<br/><br/><b>Interest rate risk.</b> Rising interest rates could cause the value of the fund's investments &#151; and therefore its share price as well &#151; to decline. Conversely, any decline in interest rates is likely to cause the fund's yield to decline, and during periods of unusually low interest rates, the fund's yield may approach zero. A low interest rate environment may prevent the fund from providing a positive yield or paying fund expenses out of current income and, at times, could impair the fund's ability to maintain a stable $1.00 share price. Over time, the total return of a money market fund may not keep pace with inflation, which could result in a net loss of purchasing power for long-term investors.<br/><br/><b>Credit risk.</b> The fund's performance could be hurt and the fund's share price could fall below $1.00 if an issuer of a money market instrument suffers an adverse change in financial condition that results in a payment default, security downgrade or inability to meet a financial obligation.<br/><br/><b>Liquidity risk.</b> The liquidity of portfolio securities can deteriorate rapidly due to credit events affecting issuers or guarantors or due to general market conditions and a lack of willing buyers. When there are no willing buyers and an instrument cannot be readily sold at a desired time or price, the fund may have to accept a lower price or may not be able to sell the instrument at all. An inability to sell one or more portfolio securities can adversely affect the fund's ability to maintain a $1.00 share price or prevent the fund from being able to take advantage of other investment opportunities.<br/><br/>Unusual market conditions, an unusually high volume of redemption requests or other similar conditions could cause the fund to be unable to pay redemption proceeds within a short period of time. If the fund is forced to sell securities at an unfavorable time and/or under unfavorable conditions, such sales may adversely affect the fund's ability to maintain a $1.00 share price.<br/><br/><b>Municipal securities risk.</b> The fund will be impacted by events in the municipal securities market. Negative events, such as severe fiscal difficulties, bankruptcy of one or more issuers, an economic downturn, unfavorable legislation, court rulings or political developments, or reduced monetary support from the federal government could hurt fund performance.<br/><br/><b>Security selection risk.</b> Although short-term securities are relatively stable investments, it is possible that the securities in which the fund invests will not perform as expected. This could cause the fund's returns to lag behind those of similar money market funds and could result in a decline in share price.<br/><br/><b>Municipal trust receipts risk.</b> The fund's investment in MTRs is subject to similar risks as other investments in debt obligations, including interest rate risk, credit risk and security selection risk. Additionally, investments in MTRs raise certain tax issues that may not be presented by direct investments in municipal bonds. There is some risk that certain issues could be resolved in a manner that could adversely impact the performance of the fund.<br/><br/><b>Tax risk.</b> Any distributions to shareholders that represent income from taxable securities will generally be taxable as ordinary income at both the state and federal levels, while other distributions, such as capital gains, are taxable to the same extent they would be for any mutual fund. New federal or state governmental action could adversely affect the tax-exempt status of securities held by the fund, resulting in a higher tax liability for shareholders and potentially hurting fund performance as well.<br/><br/><b>Counterparty risk.</b> A financial institution or other counterparty with whom the fund does business, or that underwrites, distributes or guarantees any investments or contracts that the fund owns or is otherwise exposed to, may decline in financial health and become unable to honor its commitments. This could cause losses for the fund or could delay the return or delivery of collateral or other assets to the fund.<br/><br/><b>Prepayment and extension risk.</b> When interest rates fall, issuers of high interest debt obligations may pay off the debts earlier than expected (prepayment risk), and the fund may have to reinvest the proceeds at lower yields. When interest rates rise, issuers of lower interest debt obligations may pay off the debts later than expected (extension risk), thus keeping the fund's assets tied up in lower interest debt obligations. Ultimately, any unexpected behavior in interest rates could increase the volatility of the fund's yield and could hurt fund performance. Prepayments could also create capital gains tax liability in some instances.<br/><br/><b>Regulatory risk.</b> In June 2013, the SEC proposed money market fund reform intended to address perceived systemic risks associated with money market funds and to improve transparency for money market fund investors. The Financial Stability Oversight Council (FSOC), a board of U.S. regulators established by the Dodd-Frank Act, had also previously proposed similar recommendations for money market fund reform. If one or more of the SEC or FSOC proposals for money market fund reform were to be adopted in the future, such regulatory action may affect the fund's operations and/or return potential.<b>Past Performance</b>How a fund's returns vary from year to year can give an idea of its risk. Past performance may not indicate future results. All performance figures below assume that dividends were reinvested. The<b> 7-day yield,</b> which is often referred to as the "current yield," is the income generated by the fund over a seven-day period. This amount is then annualized, which means that we assume the fund generates the same income every week for a year. For more recent performance figures and the current yield, go to www.dws-investments.com (the Web site does not form a part of this prospectus) or call the phone number included in this prospectus.<br/><br/>Performance prior to class inception is based on the performance of the fund's DWS Tax-Exempt Cash Institutional Shares, adjusted to reflect the higher expenses of Capital Assets Funds Shares. DWS Tax-Exempt Cash Institutional Shares are offered in a separate prospectus.<b>CALENDAR YEAR TOTAL RETURNS (%) (Capital Assets Funds Shares)</b>Returns for other classes were different and are not shown here.Best Quarter: 0.70%, Q2 2007 Worst Quarter: 0.00%, Q3 2003<br/>Year-to-Date as of 6/30/13: 0.02%<b>Average Annual Total Returns<br/>(for periods ended 12/31/2012 expressed as a %)</b>Total returns would have been lower if operating expenses hadn't been reduced.<br/><br/>Apex Clearing Corporation, the sole sub-distributor of Capital Assets Funds Shares, may periodically waive fees in order to maintain minimum yield levels. These waivers may be changed or terminated at any time without notice. For more recent performance information, contact the financial services firm from which you obtained this prospectus.There are several risk factors that could reduce the yield you get from the fund, cause the fund's performance to trail that of other investments, or cause you to lose money.<b>Money market fund risk. </b>An investment in the fund is not insured or guaranteed by the FDIC or any other government agency. Although the fund seeks to preserve the value of your investment at $1.00 per share, this share price isn't guaranteed, and if it falls below $1.00 you would lose money. The Advisor is not obligated to take any action to maintain the $1.00 share price. The share price could fall below $1.00 as a result of the actions of one or more large investors in the fund. The credit quality of the fund's holdings can change rapidly in certain markets, and the default of a single holding could cause the fund's share price to fall below $1.00, as could periods of high redemption pressures and/or illiquid markets.An investment in the fund is not insured or guaranteed by the FDIC or any other government agency.How a fund's returns vary from year to year can give an idea of its risk.www.dws-investments.comPast performance may not indicate future results.<div style="display:none">~ http://www.dws-investments.com/role/ScheduleShareholderFeesGovernmentAgencySecuritiesPortfolio column period compact * ~</div>
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